NO Problem: f(x,x) -> f(i(x),g(g(x))) f(x,y) -> x g(x) -> i(x) f(x,i(x)) -> f(x,x) f(i(x),i(g(x))) -> a() Proof: Matrix Interpretation Processor: dim=1 interpretation: [i](x0) = x0, [a] = 4, [f](x0, x1) = x0 + 2x1 + 4, [g](x0) = x0 orientation: f(x,x) = 3x + 4 >= 3x + 4 = f(i(x),g(g(x))) f(x,y) = x + 2y + 4 >= x = x g(x) = x >= x = i(x) f(x,i(x)) = 3x + 4 >= 3x + 4 = f(x,x) f(i(x),i(g(x))) = 3x + 4 >= 4 = a() problem: f(x,x) -> f(i(x),g(g(x))) g(x) -> i(x) f(x,i(x)) -> f(x,x) f(i(x),i(g(x))) -> a() Matrix Interpretation Processor: dim=1 interpretation: [i](x0) = x0, [a] = 0, [f](x0, x1) = 4x0 + x1 + 1, [g](x0) = x0 orientation: f(x,x) = 5x + 1 >= 5x + 1 = f(i(x),g(g(x))) g(x) = x >= x = i(x) f(x,i(x)) = 5x + 1 >= 5x + 1 = f(x,x) f(i(x),i(g(x))) = 5x + 1 >= 0 = a() problem: f(x,x) -> f(i(x),g(g(x))) g(x) -> i(x) f(x,i(x)) -> f(x,x) Unfolding Processor: loop length: 4 terms: f(x141,x141) f(i(x141),g(g(x141))) f(i(x141),i(g(x141))) f(i(x141),i(i(x141))) context: [] substitution: x141 -> i(x141) Qed